Hi I have a Janome 419S or 423S, the problem seems to be my hook race unit keeps getting loose and then the thread jams up. What can be done? Please

A jammed machine is caused by thread being caught in thehook. Remove the upper thread and the bobbin case, turn the hand wheel towardsyou (counterclockwise) by hand and remove any thread in the bobbin case area. Alwaysturn the hand wheel towards you. Turning the hand wheel away from you(clockwise) can cause the machines timing to become unaligned and jam yourmachine. Also, always make sure the presser foot is in the down position beforeyou start sewing. Sewing with the presser foot in the up position will jam yourmachine in the bobbin case. If youhave an older model sewing machine with a shuttle hook, then you can alsofollow these: 1. Disconnect the sewing machine from any power source.Loosen the thumb screw on the left side of the sewing machine body and removethe cover to expose the needle bar. This is the shaft that extends down andthat you attach a needle to for sewing. Open the shuttle race and remove the bobbinand bobbin case. 2. Turn the hand wheel toward you until the needle hasreached the lowest point of the stroke. The hook should be at the top of itsstroke inside the shuttle race. Loosen the set screw for the needle bar on theupper part of the machine, this is located on the needle bar bushing (thecollar that the needle bar slides through when making a stitch). The needle barshould slide easily up and down. 3. Turning the wheel again, adjust the position of the tipof the needle so that the upper part of the needle eye is just below the bottomedge of the hook inside the shuttle race. Once in position, re-tighten the setscrew on the needle bar bushing. Do not allow the needle bar to slip whiledoing this. 4. Replace the bobbin and bobbin case and close the shuttlerace. Thread and plug in your machine. Using a sizable scrap of cloth, sew aseam to check to see if there are any skips in the stitching. If there arestill skips re-adjust the timing again until you can sew without any skipped stitches. 5. When proper timing has been achieved replaces the coveron the needle bar and tighten the thumb screw. Hope this will help you. Good Luck.